1. Field of the Invention
The present invention relates to spinal fixation systems. Particularly, the present invention is directed to systems that fixate a portion of the skull, typically the occipital bone, to a portion of the spine for correction, fixation, and/or stabilization of a human spine.
2. Description of Related Art
Spinal fixation, such as lumbar sacral fusion and the correction of spinal deformities such as scoliotic curves, is a well known and frequently used medical procedure. Pedicle, lateral, and oblique mounting devices can be used to secure corrective spinal instrumentation to a portion of the spine that has been selected to be fused by arthrodesis.
A spinal fixation system typically includes corrective spinal instrumentation that is attached to selected vertebra of the spine by screws, hooks, and clamps. The corrective spinal instrumentation includes spinal rods or plates that are generally parallel to the patient's back. The corrective spinal instrumentation can also include transverse connecting rods that extend between neighboring spinal rods. Spinal fixation systems are used to correct problems in the lumbar and thoracic portions of the spine, and are often installed posterior to the spine on opposite sides of the spinous process and adjacent to the transverse process.
Various types of screws, hooks, and clamps have been used for attaching corrective spinal instrumentation to selected portions of a patient's spine. Examples of pedicle screws and other types of attachments are illustrated in U.S. Pat. Nos. 4,763,644; 4,805,602; 4,887,596; 4,950,269; and 5,129,388. Each of these patents is incorporated by reference as if fully set forth herein.
Fixation of the skull to the cervical spine can be used to treat trauma to the neck, degenerative diseases such as rheumatoid arthritis, and pain that is otherwise unresponsive to treatment. Current implantable devices designed to immobilize the skull with respect to the upper cervical spine have to be individually tailored. Often, such devices are assemblies of several components not designed specifically for fusing the cervical spine to the skull. However, devices specifically designed for fusing the cervical spine to the skull are currently being introduced. U.S. Pat. No. 6,146,382 issued to John Hurlbert on Nov. 14, 2000, shows one such device, the contents of this patent being incorporated herein by reference as if full set forth herein.